Voltage Regulator-Down (VRD) 10.0 Design Guide Addendum

VRD Design Guide Addendum

1 Introduction

This document defines DC-to-DC converters to meet the power requirements of desktop

computer systems using Intel

Pentium

4 processor Extreme Edition supporting Hyper-

Threading Technology

in socket 478. Requirements vary according to the needs of different

computer systems and processors that a specific voltage regulator is expected to support. The

voltage regulator-down (VRD) designation in this document refers to a voltage regulator

embedded on a motherboard, for a single processor.

Each implementation on a specific board must meet the specifications of all processors supported

by that board. The specifications in the respective processor Datasheets always take precedence

over the data in this document.

Note: A load line selection circuit is required to switch between the two processor voltage specifications

if the processor code named Prescott is to be supported in a system designed for Intel® Pentium®

processor Extreme Edition supporting Hyper-Threading Technology in socket 478. In addition,

the platform must support the full Dynamic Voltage Identification functionality of VRD10.0.

VRD 10 incorporates functional changes from prior VRD and VRM guidelines:

• Addition of dynamic voltage identification to change the output voltage during normal

operation, in response to an input from the processor.

• Simplified definition of power-good as a power-up indication (Section 6.1)

• Extended use of the VRD enable function to turn off the output in response to an input from

the processor.

• Thermal monitoring of the VRD (Section 6.2).

• Addition of V

Overshoot specification (Section 2.8)

1.1 Terminology

The following guideline categories are used throughout this document:

Term Description

REQUIRED An essential part of the design — necessary to meet processor voltage and

current specifications and follow processor layout guidelines

EXPECTED Part of Intel

processor power definitions; necessary for consistency among the

designs of many systems and power devices. May be specified or expanded by

system OEMs.

PROPOSED Normally met by this type of DC-to-DC converter and, therefore, included as a

design target. May be specified or expanded by system OEMs.